The present invention relates to an electric pump.
Japanese Laid-Open Patent Publication No. 2013-133716 describes an example of a conventional electric pump. The electric pump includes a drive shaft, which is rotated when the motor is driven, and actuation portions, which are arranged in the circumferential direction of the drive shaft and sequentially reciprocated by the rotation of the drive shaft. Each actuation portion is coupled to a diaphragm defining a pump chamber. The pump chambers are sequentially expanded and contracted to drawn in fluid from an inlet and discharge the fluid from an outlet.
An electric pump such as that described above is connected to, for example, a bladder accommodated in a vehicle seat. The bladder is inflated and deflated to stimulate the vehicle occupant.
In an electric pump such as that described above, for example, a rotary valve unit that utilizes rotation of a motor may be used to sequentially inflate and deflate a plurality of bladders accommodated in the vehicle seat. A typical rotary valve unit includes a valve body, which rotates when driven by rotational drive force of the motor, and a valve cover, which includes an inlet that draws in a fluid and a plurality of fluid outlets that discharges the fluid to the bladders. The rotary valve unit is configured to switch the fluid outlets that come into communication with the inlet of the cover in accordance with the rotational drive of the valve body. The valve body includes a body-side outlet that is opposed to the fluid outlets, which discharge the fluid to the bladders, and rotated relative to the fluid outlets. When one of the fluid outlets is opposed to (overlapped with) the body-side outlet, the fluid is discharged from the outlet. In this case, to inflate the bladders, the fluid outlet, which discharges the fluid to the bladders, needs to be opposed to the body-side outlet over a sufficient time. In this regard, for example, the body-side outlet may be arc-shaped and larger than each fluid outlet to so that the fluid outlet is opposed to the body-side inlet over a sufficient time. However, there is a limit to the size of the body-side outlet relative to the valve body. This results in the need to enlarge the valve body so that the body-side outlet can have a sufficient size or add a speed reduction unit so that the speed of the valve body can be reduced. However, this may result in enlargement of the pump.